ICD-10-CM · Other

M26.9

M26.9 identifies a dentofacial anomaly affecting the jaw, teeth, or facial skeletal structures when the documentation does not specify the exact type or subtype of anomaly.

Verified May 8, 2026 · 4 sources ↓

Status: Billable
Chapter: 13
Related CPT: 12
Region: Other

Drawn from CDCICD10DataAAPCUnboundmedicine

Documentation tips

What should appear in the chart to support M26.9.

Source · Editorial brief grounded in 4 cited references ↓

Record the specific structure involved (mandible, maxilla, alveolar ridge, dental arch) even when full characterization is pending — this may allow a more specific M26 code.
Note whether the anomaly is congenital or acquired; both map to M26.9 via approximate synonyms, but the distinction can affect surgical authorization and payer review.
Document any imaging performed (panoramic radiograph, CBCT, cephalometric analysis) and its findings, including specific measurements that could support a more precise subcategory code.
Record prior treatment history (orthodontic, surgical, prosthetic) to differentiate post-procedural sequelae from primary anomalies.
If a TMJ disorder is also present, code it separately using the appropriate M26.6x code — do not bundle it into M26.9.

Related CPT procedures

Procedure codes commonly billed with M26.9. Linking the right diagnosis to the right procedure is what establishes medical necessity.

Source · CMS LCDs · AAOS specialty guidance · claims-pattern analysis

21198 $908.84

Surgical reconstruction of a lower jaw (mandibular) segment, typically involving osteotomy and repositioning or rebuilding of bone to correct deformity from trauma, disease, or congenital origin.

21199 $906.17

Segmental mandibular osteotomy with genioglossus muscle advancement — the lower jaw is cut in segments, repositioned, and the tongue-base muscle attachment is advanced forward.

21206 $873.43

Surgical reconstruction of the maxilla (upper jaw) via osteotomy — cutting and repositioning the bone to correct deformity from trauma, congenital defect, or disease.

21247 $1,419.20

Reconstruction of the mandibular condyle using bone and cartilage harvested from the patient's own body, including autograft harvest, typically performed for congenital jaw deformity such as hemifacial microsomia.

21248 $1,023.40

Partial reconstruction of the mandible or maxilla using an endosteal implant (such as a blade or cylinder type) placed directly into the jawbone.

21249 $1,404.51

Complete reconstruction of the mandible or maxilla using an endosteal implant (blade or cylinder type) placed within the jawbone

21255 $1,221.14

Reconstruction of the zygomatic arch and glenoid fossa using bone and cartilage autografts harvested from the patient during the same operative session.

21296 $369.75

Intraoral reduction of the masseter muscle and overlying mandibular bone, typically performed for benign masseteric hypertrophy through an incision inside the mouth.

21299 $0.00

Unlisted code for a craniofacial or maxillofacial procedure on the skull or facial bones that has no specific CPT code.

70486 $128.26

Non-contrast computed tomography of the facial bones and sinuses, typically used to map facial fractures or chronic sinus disease.

70487 $151.64

Computed tomography of the facial bones and sinuses done only after intravenous contrast, used when infection, abscess, or a mass is suspected.

70488 $184.04

Facial bone and sinus CT performed in one session with a non-contrast series followed by a series after intravenous contrast.

Common coding pitfalls

The recurring mistakes coders make with M26.9 and adjacent codes.

Source · Editorial brief grounded in CDC ICD-10-CM tabular guidance, AAOS coding references, and cited references ↓

Defaulting to M26.9 when a specific subcategory applies: review M26.0–M26.89 before assigning the unspecified code — payers may flag M26.9 on claims where imaging or specialist notes clearly support a more specific code.
Confusing M26.9 with M27.8 (unilateral condylar hyperplasia or hypoplasia): the section-level Excludes 1 prohibits using M26.9 for those conditions.
Failing to check the Excludes 1 for hemifacial atrophy or hypertrophy (Q67.4), which cannot co-exist with M26.9 on the same claim.
Using M26.9 as a permanent diagnosis code in patients with fully characterized anomalies documented in specialist notes — this understates complexity and can trigger medical necessity denials for orthognathic surgery authorizations.

Clinical context

Source · Editorial summary grounded in 4 cited references ↓

Use M26.9 only when the clinical documentation clearly identifies a dentofacial anomaly but does not provide enough specificity to assign a more precise code within the M26 category. The M26 block covers a wide range of conditions — major jaw size anomalies (M26.0), jaw-cranial base relationship anomalies (M26.1), malocclusion and dental arch anomalies (M26.2), tooth position anomalies (M26.3), dentofacial functional abnormalities (M26.5), TMJ disorders (M26.6), and alveolar anomalies (M26.7). Before defaulting to M26.9, exhaust those options.

M26.9 is appropriate as a temporary working code early in a workup when imaging or specialist evaluation has not yet defined the anomaly, or as a final code only when documentation genuinely cannot be more specific. Approximate synonyms that map here include acquired or congenital anomaly of the mandible, maxillary anomaly, jaw oral deformity, and continuity defect of the mandible.

Note the section-level Excludes 1: hemifacial atrophy or hypertrophy (Q67.4) and unilateral condylar hyperplasia or hypoplasia (M27.8) cannot be coded here. If either condition is documented, redirect to the correct code. M26.9 groups under MS-DRG 157–159 (Dental and Oral Diseases) and DRGs 011–013 (Tracheostomy for face, mouth and neck diagnoses) depending on complication/comorbidity level.

Sibling codes

Other billable codes under M26 (laterality / anatomic variants).

M26.4

Malocclusion, unspecified

Frequently asked questions

Source · Generated from the editorial pipeline, verified against 4 cited references ↓

01When is M26.9 the correct final code rather than a placeholder?

M26.9 is appropriate as a final code only when the documentation genuinely cannot characterize the anomaly further — for example, an initial referral note that identifies a jaw deformity but precedes any imaging or specialist workup. Once definitive findings are available, update to the most specific M26 subcategory.

02Can M26.9 be used for both congenital and acquired jaw anomalies?

Yes. The approximate synonyms for M26.9 include both congenital anomaly of the mandible and acquired deformity of the mandible, so either etiology maps here when specificity is lacking. Document the etiology regardless, as it may affect surgical authorization.

03Is M26.9 valid on claims for orthognathic surgery?

It is technically billable, but payers frequently require a more specific diagnosis to establish medical necessity for orthognathic procedures. Use M26.9 only if no specific subcategory applies; otherwise, the unspecified code risks denial or additional documentation requests.

04What codes are excluded from use with M26.9?

The section-level Excludes 1 bars hemifacial atrophy or hypertrophy (Q67.4) and unilateral condylar hyperplasia or hypoplasia (M27.8). Neither can be coded as M26.9; use the designated codes for those conditions.

05What DRGs does M26.9 fall under?

M26.9 groups under MS-DRG 157 (Dental and Oral Diseases with MCC), 158 (with CC), and 159 (without CC/MCC), and also under DRGs 011–013 (Tracheostomy for face, mouth and neck diagnoses or laryngectomy) based on complication and comorbidity level per MS-DRG v43.0.

06Should TMJ disorders be coded under M26.9 or separately?

Separately. TMJ disorders have their own subcategory at M26.6x with laterality options (right, left, bilateral, unspecified). Do not collapse a TMJ disorder into M26.9 — doing so loses clinically relevant specificity and may not satisfy medical necessity criteria for TMJ-related procedures.

Sources & references

Editorial content was developed using the following public sources. Last verified May 8, 2026.

01CDC ICD-10-CM Tabular List 2026 (effective Oct 1, 2025)
02
icd10data.com
https://www.icd10data.com/ICD10CM/Codes/M00-M99/M26-M27/M26-/M26.9
03
aapc.com
https://www.aapc.com/codes/icd-10-codes/M26.9
04
unboundmedicine.com
https://www.unboundmedicine.com/icd/view/ICD-10-CM/872021/all/M26_9___Dentofacial_anomaly__unspecified

Mira Scribe

Mira AI Scribe captures the affected structure (mandible, maxilla, alveolar ridge), congenital versus acquired status, relevant imaging findings (CBCT, cephalometric measurements, panoramic X-ray results), and any prior orthodontic or surgical treatment from the encounter note. That detail lets coders step up from M26.9 to a specific M26 subcategory when supported, preventing downcoding, medical necessity denials, and audit exposure on orthognathic surgery or TMJ claims.

See how Mira captures M26.9 documentation